The X-Ray Coronae in NuSTAR Bright Active Galactic Nuclei

Wang, Junxian

doi:10.3847/1538-4357/ac5d49

Cited by 21 publications

(14 citation statements)

References 65 publications

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“…As very recently discussed by the authors of Kamraj et al (2022), measurements of the cut-off energy should be taken with a skeptical attitude because the values of such measurements are largely affected by the uncertainties in modeling the data and by the qual-ity of the data. Even more so, a such low cut-off energy as inferred in our distant reflection is not measured by current most sensitive observations with NuSTAR (for a sample study see Kang & Wang (2022) and for a case study see Baloković et al (2021)) nor is it expected theoretically. From a theoretical view, the inverse-Compton scattering of thermal seed photons arising from the accretion disk by the energetic particles of the corona is described by the Kompaneets equation (Kompaneets 1957).…”

Section: Discussioncontrasting

confidence: 62%

Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum

Bottacini

2022

Monthly Notices of the Royal Astronomical Society

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Ever since the launch of the NuSTAR mission, the hard X-ray range is being covered to an unprecedented sensitivity. This range encodes the reflection features arising from active galactic nuclei (AGN). Especially, the reflection of the primary radiation off the accretion disk carries the features of the manifestation of General Relativity described by the Kerr metric due to rotating supermassive black holes (SMBHs). We show the results of the broadband analyses of Mrk 876. The spectra exhibit the signature of a Compton hump at energies above 10 keV and a broadened and skewed excess at energies ∼6 keV. We establish this spectral excess to be statistically significant at 99.71 per cent (∼3σ) that is the post-trail probability through Monte Carlo simulations. Based on the spectral fit results and the significance of spectral features the relativistic reflection model is favored over the distant reflection scenario. The excess at ∼6 keV has a complex shape that we try to recover along with the Compton hump through a self-consistent X-ray reflection model. This allows inferring an upper limit to the black hole spin of a ≤ 0.85, while the inclination angle of the accretion disk results in i=32.84$^{\circ }{}^{+12.22}_{-8.99}$, which is in agreement within the errors with a previous independent measurement (i=15.4$^{\circ }{}^{+12.1}_{-6.8}$). While most spin measurements are biased toward high spin values, the black hole mass of Mrk 876 (2.4× 108 M⊙ ≤ MSMBH ≤ 1.3 × 109 M⊙) lies in a range where moderately spinning SMBHs are expected. Moreover, the analyses of twelve Chandra observations reveal for the first time X-ray variability of Mrk 876 with an amplitude of 40 per cent.

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Section: Discussioncontrasting

confidence: 62%

Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum

Bottacini

2022

Monthly Notices of the Royal Astronomical Society

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“…From Comptonization model fit to the observations, we found kT e = 15.0±1.0. Thus our results for epoch C are in agreement with that of Turner et al (2018) and Kang & Wang (2022). For the other two epochs too, we obtained low values for E cut and kT e .…”

Section: Data Availabilitysupporting

confidence: 91%

“…Also, recently, Kang & Wang (2022) from modelling of the spectrum with pexrav found a value of E cut = 54 +8 −6 keV. Similarly, from relxillCP model fits to the data, Kang & Wang (2022) found a value of kT e = 16.0±1.0.…”

Section: Data Availabilitymentioning

confidence: 81%

“…Similarly, Akylas & Georgantopoulos (2021) from modelling of the spectra using pexmon found a value of E cut of 54 +4 −4 keV. Also, recently, Kang & Wang (2022) from modelling of the spectrum with pexrav found a value of E cut = 54 +8 −6 keV. Similarly, from relxillCP model fits to the data, Kang & Wang (2022) found a value of kT e = 16.0±1.0.…”

Section: Data Availabilitymentioning

confidence: 83%

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Search for coronal temperature variation in Seyfert galaxies

Pal

Stalin

2022

Monthly Notices of the Royal Astronomical Society

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While the temperature of the X-ray corona ($\rm {kT_e}$) in active galactic nuclei (AGN) are known for many sources, its variation if any is limited to a handful of objects. This is in part due to the requirement of good signal-to-noise X-ray spectra covering a wide range of energies. We present here results on the X-ray spectral analysis of 18 Seyferts, having more than one epoch of observations to look for variation in $\rm {kT_e}$. The data for a total of 52 epochs on these 18 AGN were taken from observations carried out by NuSTAR in the 3−79 keV energy band. From phenomenological and physical model fits to the multi epoch data on these 18 sources from NuSTAR, we could constrain the cut-off energy (Ecut) in a large fraction of the sources. Also, from Comptonized model fits we could obtain $\rm {kT_e}$ for our sample. Of the 18 sources, at the 90% confidence level, evidence for variation in $\rm {kT_e}$ was found for only one source namely MCG+08-11-011. For this source between two epochs, separated by about five years, we found $\rm {kT_e}$ to decrease from 57$^{+29}_{-16}$ keV to 30$^{+11}_{-7}$ keV. During the same period, the flux decreased from (12.60 to 14.02) × 10−11 erg cm−2 s−1 and the optical depth increased from 1.68 to 2.73. We thus found a positive correlation between flux and coronal temperature with a reduction of about 40% in optical depth. Our observations tend to favour the vertically outflowing corona scenario for the observed variation in $\rm {kT_e}$ in MCG+08-11-011.

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“…However, the existence of a relation between high-energy cutoff and Eddington ratio was recently debated in the literature: Hinkle & Mushotzky (2021) and Kamraj et al (2022) find no correlation between accretion parameters and the high-energy cutoff in their new analyses of BASS AGN, as opposed to what seen by Ricci et al (2018). According to their spectral analysis of NuSTAR data alone of Swift/BAT selected AGN, Kang & Wang (2022) confirmed the absence of a E cut −λ Edd relation and, interestingly, they find that some sources fall in the runaway pair-production region of Fig. 4.…”

Section: Properties Of the X-ray Coronamentioning

confidence: 74%

The properties of the X-ray corona in the distant (z= 3.91) quasar APM 08279+5255

Bertola

Vignali

Lanzuisi³

et al. 2022

A&A

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We present new joint XMM-Newton and NuSTAR observations of APM 08279+5255, a gravitationally-lensed, broad-absorption line quasar (z = 3.91). After showing a fairly stable flux (f2 − 10 ≃ 4 − 5.5 × 10−13 erg s−1) from 2000 to 2008, APM 08279+5255 was found in a fainter state in the latest X-ray exposures (f2 − 10 ≃ 2.7 × 10−13 erg s−1), which can likely be ascribed to a lower X-ray activity. Moreover, the 2019 data present a prominent Fe Kα emission line and do not show any significant absorption line. This fainter state, coupled to the first hard X-ray sampling of APM 08279+5255, allowed us to measure X-ray reflection and the high-energy cutoff in this source for the first time. From the analysis of previous XMM-Newton and Chandra observations, X-ray reflection is demonstrated to be a long-lasting feature of this source, but less prominent prior to 2008, possibly due to a stronger primary emission. The estimated high-energy cutoff (Ecut = 99−35+91 keV) sets a new redshift record for the farthest ever measured and places APM 08279+5255 in the allowed region of the compactness-temperature diagram of X-ray coronae, in agreement with previous results on high-z quasars.

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The X-Ray Coronae in NuSTAR Bright Active Galactic Nuclei

Cited by 21 publications

References 65 publications

Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum

Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum

Search for coronal temperature variation in Seyfert galaxies

The properties of the X-ray corona in the distant (z= 3.91) quasar APM 08279+5255

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